The present invention addresses the packaging box manufacturing industry and, in particular, relates to a device for covering formed boxes, for example, boxes made from carton blanks, with a sheet of paper.
More specifically, the invention can be used especially (but not exclusively) to cover packaging boxes with parts that are difficult to access such as, for example, the inside edges of parts with complex shapes that have to be covered.
Typical boxes of this kind are folding boxes, consisting of two halves hinged along the long edges of a spine in such a way that they can be placed over each other (usually, one half fits neatly into the other) to form a box for containing products of various kinds.
As is known, these types of boxes are widely used to contain items of value sold to the public, such as perfumes, jewelry, or even CDs and DVDs.
Boxes of this kind have in fact become very popular with the public not only because they are practical but also because they are very attractive, ideal for presenting items of value.
For this reason, the quality and finish of the box covering is very important, in both structural and esthetic terms, for the box to be fully appreciated by the public.
The folding box coverings, however, present numerous difficulties on account of their relatively complex geometry and because the sheet of covering material must reach even the parts of the box that are most difficult to access.
Even greater difficulties are encountered in automatic systems when it is desired to maintain a high level of productivity during the entire process of covering the formed box so as to avoid reducing the efficiency of the production process.
At present, machines are known which cover formed boxes by applying sheets of paper to them by gluing.
In these machines, the box is first positioned precisely over the glued covering sheet, thus covering the bottom of the box.
Next, to cover the outside surfaces of the sidewalls, there are provided transversely mobile elements that move the covering sheet into contact with the corresponding outside surfaces of the walls. The edges of the covering sheet are allowed to extend upwardly past the upper edges of the walls and are later folded downwardly against the inside walls in such a way as to also cover the upper edges of the walls.
The edges of the covering material are folded by further folding elements or blades that move along the upper edges so as to glue the covering material to the box and fold its upper edges towards the inside of the box.
At this point, to complete the covering of the side walls, the free edges of the covering material are pushed against the inside surfaces of the walls by a pad or template pushed downwards vertically so that it comes into contact with the inside surfaces of the box walls.
This solution is usually effective and satisfactory when the boxes to be covered are of the “plain” type, that is to say, with a base and four walls joined to each other at the sides, without free intermediate edges to be covered which are difficult to access.
In the latter case, prior art machines do not solve the problem of covering the free intermediate edges (in this case the vertical edges but not necessarily so) in order to improve the technical and esthetic characteristics of the finished product.
Up to now, the free edges were left uncovered or, when a more elegant package was required, the covering was completed by hand, thus slowing down production and increasing costs.
Another limitation of prior art machines is the use of a mobile pad or template to cover the box edges. The template must be inserted into the box at right angles to the edges to be covered in a direction parallel to the walls of the box and in such a way that it is in contact with the inside surfaces of the box walls.
Consequently, in order to prevent the pad from interfering with the box edges and damaging the box, it must be positioned extremely accurately relative to the box, an operation that may slow down the production process.
For these reasons, a strong need is currently felt for a device and method for covering packaging boxes in full while providing high product quality in very quick time.